DENOMINATE is a 10 letter word that starts with D.

1. \De*nom"i*nate\, v. t. [imp. & p. p. {Denominated};
   p. pr. & vb. n. {Denominating}.] [L. denominatus, p. p. of
   denominare to name; de- + nominare to call by name. See
   {Nominate}.]
   To give a name to; to characterize by an epithet; to entitle;
   to name; to designate.
   
         Passions commonly denominating selfish.  --Hume.
   
   

2. \De*nom"i*nate\, a. [L. denominatus, p. p.]
   Having a specific name or denomination; specified in the
   concrete as opposed to abstract; thus, 7 feet is a denominate
   quantity, while 7 is mere abstract quantity or number. See
   {Compound number}, under {Compound}.